Conjugate fiber with moisture-absorbed elongation effect

ABSTRACT

The present invention relates to a conjugate fiber with moisture-absorbed elongation characterized by comprising a polyamide-containing component and a polyolefin-containing component. The conjugate fiber consists of the configuration of sun-moon side-by-side type or the configuration of eccentric core-sheath type. The conjugate fiber according to the present invention has a moisture-absorbed elongation effect. The length of the conjugate fiber increases by water-absorbing or moisture-absorbing, and the fiber recovers to original length after moisture-releasing.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a conjugate fiber, in which the elongation ratio thereof increases with moisture absorption or water absorption, and the length thereof recovers to original length after moisture release. More specifically, the present invention relates to a conjugate fiber which has the moisture-absorbed elongation effects after dyeing and processing steps. The present invention also relates to yarns comprising such conjugate fibers.

DESCRIPTION OF THE RELATED ART

U.S. Pat. No. 5,534,339A discloses a conjugate fiber containing a polyolefin and a polyamide which is produced by melt blowing process and mainly used in non-woven fabrics, and the conjugate fiber has a configuration of side-by-side, concentric sheath-core, eccentric sheath-core, split or islands-in-sea configurations. However, this reference does not disclose that the length of the fiber is changed with humidity.

Taiwan Patent Application No. 200804640A discloses a conjugate fiber containing polyamide and polyester polymers. The cross-section thereof is side-by-side or eccentric core-sheath types. The yarns therefrom crimp with the absorption of moisture, that is, the yarns shrink after absorption of moisture.

Fibers that are elongated after absorption of moisture and recovers to original length after moisture release, i.e. being dried, have not yet been disclosed in the prior art.

BRIEF SUMMARY OF THE INVENTION

The inventors of the present invention have surprisingly found a conjugate fiber containing a polyamide component and a polyolefin component which is consisted of a configuration of sun-moon side-by-side type or a configuration of eccentric core-sheath type. The conjugate fiber has a moisture-absorbed elongation effect. The length of the conjugate fiber increases by water-absorbing or moisture-absorbing, and the fiber recovers to original length after moisture-releasing.

In the conjugate fiber with moisture-absorbed elongation according to the present invention, the polyamide component is selected from nylon 6, nylon 66, etc.

In the conjugate fiber with moisture-absorbed elongation according to the present invention, the polyolefin component is selected from polyethylene, polypropylene and the copolymer thereof or a blend of which with polyester or polyamide.

In the conjugate fiber with moisture-absorbed elongation according to the present invention, the cross-section of the fiber is a configuration of sun-moon side-by-side type or a configuration of eccentric core-sheath.

In the conjugate fiber with moisture-absorbed elongation according to the present invention, it is a conjugate fiber consists of a configuration of eccentric core-sheath wherein the polyamide component is sheath and the polyolefin component is core.

In the conjugate fiber with moisture-absorbed elongation according to the present invention, the ratio of the polyamide component to the polyolefin component, polyamide component/polyolefin component, is 30/70 to 70/30, based on the weight ratio.

In the conjugate fiber with moisture-absorbed elongation according to the present invention, the conjugate fiber is high oriented yarn (HOY), spin drawn yarn (SDY) or draw texture yarn (DTY).

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is a cross section of a conjugate fiber with a configuration of s eccentric core-sheath type where the core portion 2 is positioned at an eccentric position in the sheath portion 1.

FIG. 2 is a cross section of a conjugate fiber with a configuration of sun-moon side-by-side type where the core portion 3 and the sheath portion 4 are bonded with each other.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a conjugate fiber characterized by comprising a polyamide component and a polyolefin component, in which the conjugate fiber consists of a configuration of sun-moon side-by-side type or a configuration of eccentric core-sheath type. The conjugate fiber has a moisture-absorbed elongation effect, where the conjugate fiber elongates after absorption of water or absorption of moisture and recovers to original length after moisture release. The present invention also relates to yarns comprising such conjugate fibers

The conjugate fiber according to the present invention is produced by bonding a polyamide component and a polyolefin component with the configuration of sun-moon side-by-side type or the configuration of eccentric core-sheath type. In the case of the configuration of eccentric core-sheath type, the core portion is composed of the polyolefin component, and the sheath portion is composed of the polyamide component. In the case of the conjugate fiber according to the present invention has the configuration of eccentric core-sheath type, the core portion is positioned at an eccentric position in the sheath portion. In the case of the configuration of sun-moon side-by-side type, the two components are bonded with each other by polymers.

Generally, after heat treatments, for example a dyeing process, the conjugate fiber according to the present invention would become a crimped state due to the difference in the shrinkage between the polyamide component and the polyolefin component, and preferably the polyolefin component is located outside the curved portion of the crimped conjugate fiber and the polyamide component is located inside the curved portion of the crimped conjugate fiber. It is because the water-absorption elongation of polyamide component is greater than that of polyolefin component. Therefore, when the conjugate fiber is subject to moisture-absorption or water-absorption, the polyamide component, i.e. inside the curved portion, has a greater elongation than the polyolefin component, i.e. outside the curved portion, and the crimped portion of the fiber becomes straight accordingly. Therefore, the fiber undergoes elongation. When the conjugate fiber is subjected to moisture-release or be dried, the fiber recovers to the crimped state due to the polyamide component, i.e. inside the curved portion, has a greater shrinkage than the polyolefin component, i.e. outside the curved portion

In the conjugate fiber of the present invention, the polyamide component is not particularly limited as long as an amide bond is comprised in the main chain thereof. The polyamide component suitable for the conjugate fiber of the present invention may be for example nylon 6, nylon 66. Generally, nylon 6 and nylon 66 are preferably used for yarn stability. In addition, it is also possible to use those with a main chain comprising an amide bond as matrix to copolymerize with other component as the polyamide component of the present invention.

In the conjugate fiber of the present invention, the polyolefin component may be polyethylene, polypropylene, polybutylene, polypentene or the like. Preferably, polyethylene, polypropylene, copolymers thereof or blends thereof is used. In addition, as the polyolefin component is not easily dyeable, a third component such as polyester, polyamide, and the like, could be added into the polyolefin component to form a blend so as to increase the dyeability of the polyolefin.

The conjugate fiber of the present invention has a cross-section in which the above mentioned polyamide component is bonded with the above mentioned polyolefin component. The polyamide component and the polyolefin component are bonded in the configuration of sun-moon side-by-side type or the configuration of eccentric core-sheath type. For elongation property, the two components are preferably bonded with the configuration of eccentric core-sheath type. The shape of the cross-section of the fiber may be a circular cross-section or a non-circular cross-section. The non-circular cross-section may be, for example, a triangular cross-section or a quadrangular cross-section. Moreover, a hollow portion may be present in the cross-section of the conjugate fiber. Moreover, the ratio of the polyamide component to the polyolefin component in the cross-section of the conjugate fiber, the polyamide component/polyolefin component is preferably 10/90 to 90/10, and more preferably 60/40 to 75/25, based on the weight ratio.

In addition, the two components comprised in the conjugate fiber according to the present invention may each independently contain pigments such as titanium oxide or carbon black, conventional antioxidants, antistatic agents, light-resistant agents and moisture-absorbing agents, compatible agents, etc.

The conjugate fiber according to the present invention is produced by the apparatus for conventional melt spinning process, wherein the melt spinning rate is preferably 2000 to 5000 m/min, more preferably 2500 to 4500 m/min, and the conjugate fibers are then wound as high oriented yarn (HOY). It is also possible to conduct the drawing directly by means of the melt spinning apparatus, and optionally the heat treatment and the drawing may be conducted simultaneously. For example, conjugate fiber is deposited in a first roller at the yarn feeding side of the extender and preheated at a temperature ranging from 50 to 100° C.; the preheated conjugate fiber is drawn between the first roller and a second roller; then the conjugate fiber is thermal set in the second roller heated to 80 to 180° C., preferably 80 to 140° C. The drawing ratio between the first roller and the second roller is set to let the resulting conjugate fiber has the desired fiber elongation, for example, preferably 1.1 to 4.0, more preferably 1.4 to 3.6, and spin drawn yarn (SDY) may be obtained. False twisting heat treatment may be optionally conducted simultaneously. For example, the processing speed is 500 m/min, the hotplate temperature is 160° C. and the drawing ratio is 1.5, after the false twisting process and winding, the draw texture yarn (DTY) is obtained.

The conjugate fiber with moisture-absorbed elongation according to the present invention is subjected to boiling water treatment for 40 minutes with a load of 6.6*10−4 g/d to be stabilized. After heat treatment, the conjugate fiber is applied with a load of 6.6*10−4 g/d and then resting at a relative humidity of 60% and a temperature of 25° C. for 2 hours, and then measuring the length thereof as L0. Water is sprayed to the conjugate fiber with sprayer and after 1 minute, measuring the length thereof as L1. The elongation ΔL is shown as below:

^(Δ) L=(L1−L0)*100/L0

The conjugate fiber according to the present invention has ^(Δ)L of 0.5 or more, preferably 1.0 to 35.0, more preferably 1.5 to 30.0

EXAMPLES

The following examples will provide further explanation of the invention, while the invention is not limited thereto.

Example 1

Nylon 6 and polypropylene were melted at 275° C., and using an eccentric core sheath type nozzle wherein nylon 6 was used as a sheath and polypropylene was used as a core in a compound ratio of 70:30 to form an eccentric core sheath type fiber, and then the fiber was cooled and cured. After application of an oil agent, the yarn was wound at a rate of 3700 m/min to give 75 d/72f HOY of a conjugate fiber with moisture-absorbed elongation. The results were shown in Table 1.

Example 2

Nylon 6 and polypropylene were melted at 275° C., and using an eccentric core sheath type nozzle wherein nylon 6 was used as a sheath and polypropylene was used as a core in a compound ratio of 70:30 to form an eccentric core sheath type fiber, and then the fiber was cooled and cured. After application of an oil agent, the yarn was preheated at a first roll with a temperature of 60° C. at a rate of 2500 m/min, and the yarn was then subjected to stretching (stretch ratio 1.6 times) and heat treatments at a second roller heated to 130° C., and the yarn was wound to give 75 d/72f SDY of a conjugate fiber with moisture-absorbed elongation.

Example 3

Nylon 6 and polypropylene were melted at 275° C., and using an eccentric core sheath type nozzle wherein nylon 6 was used as a sheath and polypropylene was used as a core in a compound ratio of 70:30 to form an eccentric core sheath type fiber, and then the fiber was cooled and cured. After application of an oil agent, the yarn was wound at a rate of 2500 m/min to give 120 d/72f POY of a conjugate fiber. The fiber further underwent a false twisting process with a processing speed of 500 m/min, a hotplate temperature of 160° C. and a drawing ratio of 1.6, and then winding to give 75 d/72f DTY of a conjugate fiber with moisture-absorbed elongation.

Example 4

Nylon 6 and polypropylene were melted at 275° C., and using an eccentric core sheath type nozzle wherein nylon 6 was used as a sheath and a polymer blend of polypropylene with 10% polyamide was used as a core in a compound ratio of 70:30 to form an eccentric core sheath type fiber, and then the fiber was cooled and cured. After application of an oil agent, the yarn was wound at a rate of 3700 m/min to give 75 d/72f HOY of a conjugate fiber with moisture-absorbed elongation.

Example 5

Nylon 6 and polyethylene were melted at 275° C., and using an eccentric core sheath type nozzle wherein nylon 6 was used as a sheath and polyethylene was used as a core in a compound ratio of 70:30 to form an eccentric core sheath type fiber, and then the fiber was cooled and cured. After application of an oil agent, the yarn was wound at a rate of 3700 m/min to give 75 d/72f HOY of a conjugate fiber with moisture-absorbed elongation.

Example 6

Nylon 66 and polyethylene were melted at 275° C., and using an eccentric core sheath type nozzle wherein nylon 66 was used as a sheath and polyethylene was used as a core in a compound ratio of 70:30 to form an eccentric core sheath type fiber, and then the fiber was cooled and cured. After application of an oil agent, the yarn was wound at a rate of 3700 m/min to give 75 d/72f HOY of a conjugate fiber with moisture-absorbed elongation.

Example 7

Nylon 6 and polypropylene were melted at 275° C., and using an eccentric core sheath type nozzle wherein nylon 6 was used as a sheath and polypropylene was used as a core in a compound ratio of 55:45 to form an eccentric core sheath type fiber, and then the fiber was cooled and cured. After application of an oil agent, the yarn was wound at a rate of 3500 m/min to give 75 d/72f HOY of a conjugate fiber with moisture-absorbed elongation. The results were shown in Table 1.

Example 8

Nylon 6 and polypropylene were melted at 275° C., and using a sun-moon side-by-side type nozzle wherein nylon 6 was used as a sheath (i.e. moon) and polypropylene was used as a core (i.e. sun) in a compound ratio of 70:30 to form a sun-moon side-by-side type fiber, and then the fiber was cooled and cured. After application of an oil agent, the yarn was wound at a rate of 3500 m/min to give 75 d/72f HOY of a conjugate fiber with moisture-absorbed elongation. The results were shown in Table 1.

Comparative Example 1

Nylon 6 and polypropylene were melted at 275° C., and using a concentric core sheath type nozzle wherein nylon 6 was used as a sheath and polypropylene was used as a core in a compound ratio of 70:30 to form a concentric core sheath type fiber, and then the fiber was cooled and cured. After application of an oil agent, the yarn was wound at a rate of 3700 m/min to give 75 d/72f HOY of a conjugate fiber with moisture-absorbed elongation.

Comparative Example 2

Polyethylene terephthalate with a lower intrinsic viscosity of 0.5 and polyethylene terephthalate with a higher intrinsic viscosity of 0.64 were melted at 290° C., and using an eccentric core sheath type nozzle wherein the polyethylene terephthalate with a lower intrinsic viscosity was used as a sheath and the polyethylene terephthalate with a higher intrinsic was used as a core in a compound ratio of 70:30 to form an eccentric core sheath type fiber, and then the fiber was cooled and cured. After application of an oil agent, the yarn was wound at a rate of 3700 m/min to give 75 d/72f HOY of a conjugate fiber.

Comparative Example 3

Polyethylene terephthalate with a lower intrinsic viscosity of 0.5 and polyethylene terephthalate with a higher intrinsic viscosity of 0.64 were melted at 290° C., and using a sun-moon side-by-side type nozzle wherein the polyethylene terephthalate with a lower intrinsic viscosity was used as a sheath (i.e. moon) and the polyethylene terephthalate with a higher intrinsic was used as a core (i.e. sun) in a compound ratio of 70:30 to form a sun-moon side-by-side type fiber, and then the fiber was cooled and cured. After application of an oil agent, the yarn was wound at a rate of 3700 m/min to give 75 d/72f HOY of a conjugate fiber.

The conjugate fibers according to the Examples and Comparative Examples above were determined based on the methods below.

(1) Change of Shape

The yarn was knitted (3″/190 needles) by a knitting machine, dyed with acidic dyes at 100° C., washed and dried to be used as a testing sample. Water is sprayed into the fabric with a sprayer, and observing the fabric after water is absorbed. After water dripping down, the bulkiness and shrinkage of the mesh of the fabric were determined by naked eye observation.

Mesh change 1: the mesh elongates a lot (space become larger) after water dripping down

Mesh change 2: the mesh does not change after water dripping down

Mesh change 3: the mesh shrinks obviously (space become smaller) after water dripping down

(2) Moisture-Absorbed Elongation

Reeled yarns were made by using the conjugate fibers, and they were subjected to boiling water treatment for 40 minutes with a light load of 6.6*10-4 g/d. A load of 6.6*10-4 g/d is applied thereto and resting for 2 hours, and then measuring the length thereof as L0. Water is sprayed to the conjugate fiber with sprayer and after 1 minute, measuring the length thereof as L1. The elongation ΔL is shown as below:

^(Δ) L=(L1−L0)*100/L0

TABLE 1 Change of Moisture- shape of absorbed the fabric elongation Example 1 1 +2.6 Example 2 1 +27.8 Example 3 1 +12.6 Example 4 1 +2.4 Example 5 1 +1.6 Example 6 1 +4.6 Example 7 1 +2.0 Example 8 1 +3.5 Comparative Example 1 2 +0 Comparative Example 2 2 +0 Comparative Example 3 2 +0.1 

What is claimed is:
 1. A conjugate fiber with moisture-absorbed elongation characterized by comprising a polyamide component and a polyolefin component, which is consisted of a configuration of sun-moon side-by-side type or a configuration of eccentric core-sheath type; the conjugate fiber has a moisture-absorbed elongation effect, and the length of the conjugate fiber increases by water-absorbing or moisture-absorbing, and the fiber recovers to original length after moisture-releasing.
 2. The conjugate fiber with moisture-absorbed elongation according to claim 1, in which the polyamide component is nylon 6 or nylon
 66. 3. The conjugate fiber with moisture-absorbed elongation according to claim 1, in which the polyolefin component is polyethylene, polypropylene and the copolymer thereof or a blend of which with polyester or polyamide.
 4. The conjugate fiber with moisture-absorbed elongation according to claim 1, in which the cross-section thereof is a configuration of sun-moon side-by-side type or a configuration of eccentric core-sheath.
 5. The conjugate fiber with moisture-absorbed elongation according to claim 1, which is high oriented yarn (HOY), spin drawn yarn (SDY) or draw texture yarn (DTY).
 6. A yarn comprising the conjugate fiber with moisture-absorbed elongation according to claim
 1. 